Seawater To Cool Downtown Honolulu

Cold deep-sea water will be used to cool buildings in downtown Honolulu, Hawaii. A five-foot-wide pipeline with an intake hundreds of feet below the sea will pull in cold water, which will circulate through air-conditioning units around the city.

Honolulu Seawater Air Conditioning LLC, which is undertaking the $240 million project, expects its technology to cut the Hawaiian city’s air conditioning electricity usage by up to 75 percent while slashing carbon emissions and the use of ozone-depleting refrigerants.

A somewhat more subtle system for using sea water was envisioned by Neal Stephenson in his 1995 novel The Diamond Age; the smartcoral reef.

...an inverted tree of rootlike plumbing that spread fractally through the bedrock of New Chusan, terminating in the warm water of the South China Sea as numberless capillaries arranged in a belt around the smartcoral reef, several dozen meters beneath the surface. One big huge pipe gulping up seawater would have done roughly the same thing...

But it wouldn't have been ecological... Thus, water seeped into Source Victoria through microtubes, much the same way it seeped into a beach.
(Read more about Neal Stephenson's smartcoral reef)